During a surprise visit Tuesday to Afghanistan, where he signed an agreement outlining the U.S. role there after most NATO forces leave in 2014, President Barack Obama said he knew many Americans are tired of the war, but underscored a need to "finish the job."

"Our goal is to destroy al-Qaida, and we are on a path to do exactly that," Mr. Obama said. The election-year speech aired live in the U.S. during prime-time hours.